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EP1814276A1 - Procédé pour la compensation de bruit de phase dans un récepteur MDFO, et dispositif et récepteur correspondants - Google Patents

Procédé pour la compensation de bruit de phase dans un récepteur MDFO, et dispositif et récepteur correspondants Download PDF

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Publication number
EP1814276A1
EP1814276A1 EP06425037A EP06425037A EP1814276A1 EP 1814276 A1 EP1814276 A1 EP 1814276A1 EP 06425037 A EP06425037 A EP 06425037A EP 06425037 A EP06425037 A EP 06425037A EP 1814276 A1 EP1814276 A1 EP 1814276A1
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EP
European Patent Office
Prior art keywords
ofdm
signals
receiver
subcarriers
phase noise
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06425037A
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German (de)
English (en)
Inventor
Gerlando Alletto
Giambattista Di Donna
Stefano Pasquin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nokia Solutions and Networks SpA
Original Assignee
Siemens SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens SpA filed Critical Siemens SpA
Priority to EP06425037A priority Critical patent/EP1814276A1/fr
Priority to US11/657,915 priority patent/US20070189403A1/en
Publication of EP1814276A1 publication Critical patent/EP1814276A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03375—Passband transmission
    • H04L2025/03414—Multicarrier
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03433—Arrangements for removing intersymbol interference characterised by equaliser structure
    • H04L2025/03439—Fixed structures
    • H04L2025/03522—Frequency domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0024—Carrier regulation at the receiver end
    • H04L2027/0026—Correction of carrier offset
    • H04L2027/0038—Correction of carrier offset using an equaliser
    • H04L2027/0042—Correction of carrier offset using an equaliser the equaliser providing the offset correction per se

Definitions

  • the present invention refers to wireless communication systems utilising OFDM/OFDMA (Orthogonal Frequency Division Multiplexing/orthogonal Frequency Division Multiple Access) techniques, and more particularly it concerns a method of and device for mitigating oscillator phase noise effects in OFDM/OFDMA receivers.
  • OFDM/OFDMA Orthogonal Frequency Division Multiplexing/orthogonal Frequency Division Multiple Access
  • Orthogonal Frequency Division Multiplexing is a transmission technique proposed in recent years for different applications, such as Digital Video Broadcasting and high bit rate Wireless Local Area Networks.
  • an information symbol modulates a set of frequencies and is detected at a receiver by means of a Discrete Fourier Transform (DFT).
  • DFT Discrete Fourier Transform
  • OFDM is scarcely sensitive to selective fading, which will affect at most some the frequencies in the set and not a whole message.
  • OFDM is very sensitive to frequency offset and phase noise.
  • the present invention is concerned with phase noise effect mitigation.
  • phase noise directly at its source, that is the oscillators; others exploit the particular modulation adopted, by introducing an ad hoc signal processing on the received modulated signal.
  • the latter category gives in general better results, especially from the point of view of reliability, and the invention belongs to such a category.
  • CPE Common Phase Error
  • ICI inter-carrier interference
  • EP-B 0 933 903 An example is disclosed in EP-B 0 933 903 .
  • the document discloses a receiver with compensation circuit acting before the DFT, hence in the time domain.
  • the circuit calculates a product between the Ng corresponding samples in the guard interval at the beginning and the end of the OFDM symbol. That product generates an error signal whose angle ⁇ m is just the phase variation across the N samples of the m-th OFDM symbol.
  • a linear interpolation gives the sample-by-sample phase evolution required to correct the ICI, and the result of the interpolation is used to generate a signal with a reduced degradation.
  • phase sampling interval equal to OFDM symbol interval
  • linear interpolation performed which assumes a constant sample-by-sample phase difference. No indication about the method performance in reducing phase noise is provided.
  • WO-A 03/047196 proposes a method in which a received OFDM symbol is split into a plurality of sequential segments in the time domain and a DFT is separately performed on each segment.
  • the pilot sub-carriers allow estimating the phase of each segment; by subtracting the common contribute due to the channel, the phase noise angle is identified and then cancelled for each segment in the time domain.
  • the whole OFDM symbol can be recomposed and submitted to a DFT for data decoding.
  • the method reduces the phase estimate interval, yet it is rather complex. Again, no performance results are given.
  • US-A 2004/0171366 proposes a method of suppressing phase noise downstream the DFT in an OFDM-based WLAN conforming to IEEE Standard 802.11a.
  • the method estimates the CPE from the pilot subcarriers and the ICI plus noise energy from the null sub-carriers.
  • the estimated quantities are used to determine coefficients c(k) of an MMSE equaliser, consisting in a coefficient for each data sub-carrier and providing an estimate of THE received data.
  • the simulation results show that the performance of a receiver employing the method is rather close to those for a situation of phase noise absence.
  • the method is computationally complex, since it requires the previous estimation of the CPE and ICI and uses an equaliser coefficient for each data subcarrier (48 according to IEEE Standard 802.11a).
  • the complexity is still greater for use in WLANs according to more recent standards, such as IEEE 802.16-2004, where 192 data subcarriers are envisaged.
  • the invention provides a method in which a received OFDM signal, after having undergone a Discrete Fourier Transform to be converted into frequency domain, is submitted to a linear transversal equalisation operating on all subcarriers of the orthogonal frequency multiplex and based on a number of coefficients far lower than a number of said subcarriers.
  • the invention provides a device connected downstream a Fourier transformer converting time-domain samples of received OFDM signals into signals in the frequency domain. wherein said device comprises a linear transversal equaliser operating on all subcarriers of the orthogonal frequency division multiplex and having a number of taps far lower than a number of said subcarriers.
  • the device comprises 3 to 7 taps.
  • the invention also concerns a receiver employing the compensation method and device of the invention.
  • the receiver is a receiver for a wireless local area network according conforming IEEE Standard 802.
  • the core idea of this invention is the adoption of a Linear Transversal Equaliser (LTE) working in the frequency domain for reducing both the CPE and the ICI caused by the phase noise as loss of orthogonality of the OFDM signal.
  • LTE Linear Transversal Equaliser
  • the LTE is a well known equalising structure in the time domain, where it has been employed for counteracting the ISI (Inter Symbol Interference) among adjacent information symbols, generated by the transmission channel in a convolutional form.
  • ISI Inter Symbol Interference
  • the phase noise affects the received OFDM signal in the time domain in a multiplicative form.
  • OFDM receivers include DFT (Discrete Fourier Transformer) to decode the information symbols, which thereafter are in the frequency domain, where the phase noise has become a convolutional disturb signal. That is why a LTE, working in the frequency domain, is powerful in reducing the ICI and the CPE as well.
  • DFT Discrete Fourier Transformer
  • the first 28 subcarriers (numbered -128 to -101) and the last 27 subcarriers (numbered -101 to 127) are non-modulated subcarriers (usually referred to as null subcarriers) forming guard intervals in respect of the adjacent channels.
  • subcarrier 0, corresponding to the d.c. component is a non-modulated subcarrier.
  • the remaining 200 subcarriers include 192 data subcarriers, which are modulated by QAM information symbols, and 8 pilot subcarriers, which are modulated by QPSK symbols that are defined by the standard, and being therefore known to the receiver, can be used at the receiver for estimation purposes.
  • data subcarriers which are modulated by QAM information symbols
  • 8 pilot subcarriers which are modulated by QPSK symbols that are defined by the standard, and being therefore known to the receiver, can be used at the receiver for estimation purposes.
  • known signals the signals conveyed by the null and pilot subcarriers
  • unknown signals the information symbols conveyed by the data subcarriers
  • samples r(n) of a received OFDM signal transmission are fed to a Discrete Fourier Transformer (DFT) 1 after downconversion to baseband and analogue-to-digital conversion in conventional conversion units, not shown in the drawing.
  • DFT Discrete Fourier Transformer
  • s(n) are the transmitted signals
  • h(n) is the channel impulse response
  • ⁇ is the convolution symbol
  • ⁇ (n) is the phase noise
  • ⁇ (n) is the additive white Gaussian noise (AWGN).
  • AWGN additive white Gaussian noise
  • DFT Discrete Fourier Transformer 1 transforms signals r(n) into signals x(k) in the frequency domain and feeds the frequency-domain samples to a parallel-to-serial converter (P/S) 2 and to a channel estimator 3.
  • P/S parallel-to-serial converter
  • Compensator 10 which is the subject matter of the invention, essentially consists of a Linear Transversal Equaliser (LTE) 4 and of the means for computing and optimising the equaliser coefficients (tap values) c(i) at each OFDM symbol.
  • LTE Linear Transversal Equaliser
  • the optimisation criterion is for instance the MMSE (Minimum Mean Square Error).
  • MMSE Minimum Mean Square Error
  • the structure of a Linear Transverse Equaliser is well known and is widely disclosed in the literature. Reference can be made for instance to the book of S. Benedetto, E. Biglieri and V. Castellani "Digital Transmission Theory", Prentice-Hall, 1987.
  • M is in the range 1 to 3.
  • the equaliser output y(k) is then fed to a symbol estimator 5 that provides estimation â(k) of each received OFDM symbol.
  • Symbol estimators are well known in the art and need not to be disclosed in detail.
  • phase noise corrector 100 estimates the symbols transmitted on the data sub-carriers and uses the symbols on all subcarriers for determining the best values of the LTE taps.
  • a multiplier 8 receives either known symbols a P (k) or estimated OFDM symbols â(k) and multiplies them by a channel estimate H(k) supplied by channel estimator 3.
  • Channel estimation in estimator 4 is performed by known methods, for instance, as disclosed in the papers " On channel estimation in OFDM systems " by J.J. Van de Beek et al., Proceedings IEEE, Vehicular Technology Conference, vol. 2, Chicago, July 1995 , or " OFDM channel estimation by singular value decomposition " by O. Edfors et al., IEEE Transactions on Communications, pp. 931-939, July 1998 .
  • Output signal d(k) of multiplier 8 is fed to an input of a subtractor 9, which has a second input connected to the output of LTE 5 and supplies LTE with error ⁇ (k).
  • the optimisation criterion is the MMSE (Minimum Mean Square Error).
  • DSP digital signal processor
  • the second phase can be repeated if all coefficients have not reached their steady state values.
  • simulation results have shown that convergence to the steady state values happens after only one or two repetitions.
  • the step size ⁇ is an empirical trade-off between the convergence speed and the steady state residual error in the tap values (with respect to those calculated by (7)).
  • LTE 4 is to be implemented with a faster technology than required for the LTEs conventionally used for intersymbol interference compensation, where the coefficients are slowly variable in time and their convergence is a continuous process.
  • thermal noise has been considered absent and the channel transfer function H(k) has been ideally estimated at each sub-carrier frequency.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)
EP06425037A 2006-01-26 2006-01-26 Procédé pour la compensation de bruit de phase dans un récepteur MDFO, et dispositif et récepteur correspondants Withdrawn EP1814276A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP06425037A EP1814276A1 (fr) 2006-01-26 2006-01-26 Procédé pour la compensation de bruit de phase dans un récepteur MDFO, et dispositif et récepteur correspondants
US11/657,915 US20070189403A1 (en) 2006-01-26 2007-01-25 Method and device for phase noise compensation in OFDM/OFDMA receivers, and receiver employing the method and the device

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Application Number Priority Date Filing Date Title
EP06425037A EP1814276A1 (fr) 2006-01-26 2006-01-26 Procédé pour la compensation de bruit de phase dans un récepteur MDFO, et dispositif et récepteur correspondants

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2592801A1 (fr) * 2011-11-09 2013-05-15 Mediatek Inc. Récepteur de communication sans fil avec évaluation du bruit de phase et compensation de bruit de phase effectuée après l'évaluation du canal et procédé de réception de communication sans fil associé
CN104702558A (zh) * 2013-12-05 2015-06-10 上海数字电视国家工程研究中心有限公司 Ofdm系统的相位噪声消除方法
CN111130660A (zh) * 2019-12-16 2020-05-08 天津津航计算技术研究所 一种相位噪声测量探头电路

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US8855580B2 (en) * 2008-06-27 2014-10-07 Telefonaktiebolaget L M Ericsson (Publ) Methods and apparatus for reducing own-transmitter interference in low-IF and zero-IF receivers
US8090320B2 (en) * 2008-12-19 2012-01-03 Telefonaktiebolaget Lm Ericsson (Publ) Strong signal tolerant OFDM receiver and receiving methods
US20140270015A1 (en) * 2012-06-28 2014-09-18 Vladimir Kravtsov Inter-carrier interference phase noise compensation based on phase noise spectrum approximation
US8897412B2 (en) * 2012-12-14 2014-11-25 Intel Corporation Method and apparatus for phase noise mitigation
US9209852B2 (en) * 2013-09-23 2015-12-08 Maxlinear, Inc. Modular microwave backhaul outdoor unit
US9686114B2 (en) * 2015-06-26 2017-06-20 Futurewei Technologies, Inc. Apparatus, method, and computer program for communicating one or more symbols with multiple pilot signals and nulls
CN107947839B (zh) * 2017-11-27 2020-09-29 电子科技大学 用于大规模mimo系统的相位噪声补偿抑制方法

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US6233276B1 (en) * 1999-09-13 2001-05-15 Virata Corporation XDSL modem having time domain filter for ISI mitigation
WO2003047196A2 (fr) 2001-11-29 2003-06-05 Dibcom Procede et dispositif de demodulation avec compensation du bruit de phase
US20040171366A1 (en) 2002-12-10 2004-09-02 Yeheskel Bar-Ness Method for phase noise suppression for OFDM based WLANs
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WO2003047196A2 (fr) 2001-11-29 2003-06-05 Dibcom Procede et dispositif de demodulation avec compensation du bruit de phase
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2592801A1 (fr) * 2011-11-09 2013-05-15 Mediatek Inc. Récepteur de communication sans fil avec évaluation du bruit de phase et compensation de bruit de phase effectuée après l'évaluation du canal et procédé de réception de communication sans fil associé
TWI461006B (zh) * 2011-11-09 2014-11-11 Mediatek Inc 無線通訊接收機、無線通訊接收方法與相位雜訊補償裝置
US9036747B2 (en) 2011-11-09 2015-05-19 Mediatek Inc. Wireless communication receiver with phase noise estimation and phase noise compensation performed after channel estimation, and related wireless communication receiving method and phase noise compensation apparatus
CN104702558A (zh) * 2013-12-05 2015-06-10 上海数字电视国家工程研究中心有限公司 Ofdm系统的相位噪声消除方法
CN104702558B (zh) * 2013-12-05 2018-03-09 上海数字电视国家工程研究中心有限公司 Ofdm系统的相位噪声消除方法
CN111130660A (zh) * 2019-12-16 2020-05-08 天津津航计算技术研究所 一种相位噪声测量探头电路
CN111130660B (zh) * 2019-12-16 2022-04-19 天津津航计算技术研究所 一种相位噪声测量探头电路

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